Abstract: A hybrid RADAR and communication system provides both RADAR and wireless communication (COMMS) that share the same antenna, transmit and receive amplifiers, and other hardware, thereby reducing size, weight, and power requirements. In embodiments, COMMS implementation only requires adding additional software to a RADAR system. Embodiments are EW/COMMS systems that provide electronic warfare and wireless communication. EW/COMMS embodiments facilitate communication in hostile environments by enabling data exchange at any frequency within a broad EW frequency range. Communication signals can be obfuscated by interleaving them with EW waveforms at the same RF frequency. Collaborative communication between EW systems is enhanced by reducing EW communication lag times.

Abstract: An apparatus having an analog-to-digital converter with an increased effective resolution is disclosed. The apparatus includes a signal processing functional block and an analog-to-digital conversion block. The signal processing functional block includes a controller for providing a set of digital control signals according to a set of digital input signals received by the controller, a digital-to-analog converter for converting the digital control signals to a set of corresponding analog control signals, and a physical hardware unit for performing a specific function according to the analog control signals. The analog-to-digital conversion block includes an adder for adding a dither signal to an analog feedback signal originated from the physical hardware unit, an ADC for converting sums of dither signals and analog feedback signals to a set of oversampled digital control signals to be fed into the controller.

Abstract: A nutation controller and methods of use correct for the small, fixed offset inherent in laser communication systems referred to as pointing bias error, thereby removing the pointing bias error and allowing for more robust and rapid laser communications between distant platforms.

Abstract: A disclosed apparatus and method verify whether a hot spot within a scene is a valid laser-com signal, and further identify laser-com signals of interest. An extended Kalman filter (EKF) is applied to a received signal or beacon to detect whether it is modulated according to a square wave or other expected amplitude modulation pattern. Embodiments further determine whether the modulation frequency matches a signal or beacon of interest. In embodiments, a plurality of indexed EKF's are “tuned” to different modulation frequencies, and are used to identify a beacon's modulation frequency index. Where each EKF is required to compute amplitude and phase partial derivatives of the observation vector, the amplitude partials can be calculated according to the expected modulation pattern, and the phase partials can be calculated using a truncated Fourier or step-wise approximation of the expected modulation pattern. Embodiments further assume a time-invariant covariance matrix.

Abstract: The Quad Cell permits measurement of four quadrant signal powers simultaneously, metrics which are equal when the laser spot is at the desired zero location, at the center of the cell, the origin of the cells' axes. A control action acts upon the Quad Cell signals to move the laser spot toward the origin of the axes bisecting the four quadrants of the cell, moving the laser spot to the origin to achieve a null in the difference between these four signal levels.

Abstract: A disclosed apparatus and method detect light source “hotspots” and recognize laser communication signals within a scene, while minimizing repeat consideration of previously detected light sources. Local maxima are identified in pixel frames from a focal plane array (FPA), and compared with a table of previous detections. FPA frames can be used directly for hotspot detection, or successive FPA frames can be subtracted for edge detection. Most recent detection frame numbers, coordinates, signal values, and/or other information can be updated in the table upon repeat detection of a hotspot. Source identifying information can be included in the table for entries that are identified as laser communication signals. Source identifying features can be evaluated so that only signals of interest are saved in the table. Hotspots that remain undetected after a designated number of frames can be deleted from the table.

Abstract: An apparatus and method for tracking a laser communication signal of interest incident on a focal plane array (FPA) identifies a plurality of “hotspots” in a scene of interest, and aligns a hotspot that is a signal of interest (SOI) or beacon component thereof with the FPA. Hotspot centroids can be estimated within a fraction of an FPA pixel by considering squares of four pixels and comparing their signal amplitudes. A multi-spot calculation is used to improve the position estimates of all of the hotspots by applying a Kalman filter to the hotspot position data and assuming that the relative hotspots positions are fixed. The calculation is periodically repeated to enable tracking of the SOI. Amplitude variability of the hotspots is accommodated by weighting the hotspot contributions according to their intensities. In embodiments, estimation error of the SOI centroid is less than a smallest dimension of the FPA pixels.

Abstract: A system and method of assisting a radio in finding a network is presented. A method first detects existing nodes. A message is received on a slow communication link in a slow network from a new node. One or more existing nodes are found that may connect to new node with a fast communication link in a fast network. The fast network has a data rate that is faster than the slow network. A message is transmitted over the slow network to the new node to provide the new node possible existing nodes that are near it that it may connect to. Based on that message the new node establishes a fast communications link on the fast network between the new node and an existing node. The fast communications link can be a directional link.

Abstract: A system and method for generating a low probability of detection (LPD) waveform is presented. The method modulates pre-modulated symbols using pulse-position modulation (PPM) to produce PPM modulated signals with a modulated in-phase (I) component and a modulated quadrature (Q) component. Next, frequency hopping is used to transmit the modulated I component at a randomized start time within a time slot and to transmit the modulated Q component at the randomized start time within the same slot. The modulated Q component does not overlap with the modulated I component. The method can also overlay transmission security (TRANSEC) pseudorandom (PN) overlay on the modulated Q component and the modulated I component before the modulated Q component and the modulated I component are transmitted.

Abstract: A system and method for calculating a time of arrival (TOA) of an electromagnetic signal is presented. A method receives a fast Fourier transform (FFT) signal that is a FFT of an original electromagnetic signal containing symbol data. The FFT signal is either multiplied or divided with a value to remove the symbol data. Removing the symbol data generates a perturbed data values representing perturbed signal with a perturbed covariance. The method calculates a perturbed covariance of the perturbed data values. After the perturbed covariance is calculated, the method at least partially corrects the perturbed covariance to produce a corrected covariance. The TOA of the original electromagnetic signal is calculated based, at least in part, on the perturbed covariance.

Abstract: A system and method for calculating a time of arrival (TOA) of an electromagnetic signal is presented. A method receives a fast Fourier transform (FFT) signal that is a FFT of an original electromagnetic signal containing symbol data. The FFT signal is either multiplied or divided with a value to remove the symbol data. Removing the symbol data generates a perturbed data values representing perturbed signal with a perturbed covariance. The method calculates a perturbed covariance of the perturbed data values. After the perturbed covariance is calculated, the method at least partially corrects the perturbed covariance to produce a corrected covariance. The TOA of the original electromagnetic signal is calculated based, at least in part, on the perturbed covariance.

Abstract: A two-axis satellite antenna mounting and tracking assembly including a universal joint for mounting the antenna to support structure. A pair of linear actuators offset at 90.degree. to each other about the universal joint are operated in full-on/full-off fashion to control the azimuth and elevation orientations of the antenna. Satellite tracking is effected by maximizing received signal strength.

Abstract: An arrangement for stabilizing the line of sight in an optical tracking system relative to inertial space over a specified range of frequencies utilizing a mirror/torquer/pickoff subassembly both as an inertial sensor and as a control effector.

Abstract: An arrangement for stabilizing the line of sight in an optical tracking system by isolating the line of sight from angular vibration induced by the coarse positioning system. The tracking error of the coarse positioning system is transformed from its existing coordinate system onto the line of sight (scene) coordinates and this transformed error is utilized for stabilization.

Abstract: To stabilize the line-of-sight of an optical image relative to a commanded line-of-sight, a stabilization system consisting of a mirror having two limited degrees of freedom, a two axis gyroscope having its two sensitive axes perpendicular to the LOS, a pickoff sensor feeding back mirror angular position, servo compensators that provide mirror torque commands to a two axis mirror torquer, and the electronic hardware that ties these components together is used.